Welcome to the Forum. As you imply, HSV can mimic Herpes
ZosterChickenpox - vaccine
Herpes zoster
Herpes zoster (shingles) - close-up of lesion
Herpes zoster (shingles) on the arm
Herpes zoster (shingles) on the back
Herpes zoster (shingles) on the chest
Herpes zoster (shingles) on the hand
Herpes zoster (shingles) on the hand and fingers
Herpes zoster (shingles) on the neck and cheek
Herpes zoster (shingles), disseminated
Zoster vaccine live when it occurs at non-genital areas and without a culture it is sometimes hard to determine which is causing a rash such as the one you had 3.5 years ago. The time course with
neuralgiaCluster headaches
Neuralgia
Trigeminal neuralgia following the initial outbreak is certainly consistent with zoster. In addition however, I would also point out that there are many other things that can also cause the sort of discomfort you are currently experiencing at your thigh, amongst them back strain brought on by a long day at work.
Regarding your current rash, i would also point out the zoster can recur, as does HSV. In fact about 20% of persons who have had zoster will get a recurrence. My advice at this time would be to go see your doctor, preferably the one who say you for your prior episode (continuity is a good thing). The sooner you can see him/her the better since if this is indeed zoster the sooner therapy is started the more relief you will get. My guess this is recurrent zoster but without the opportunity to evaluate you directly this is just a guess. The answer lies with your doctor.
Hope this helps. EWH